The biggest train drivers' union has suspended a strike ballot it had just started among its members on Southern Railway because of "technical difficulties".

Aslef had asked its members if they wanted to take industrial action in a dispute over driver only trains. The result of the ballot was due within two weeks, raising the threat of strikes at the end of the month.

Southern still faces a series of strikes in the coming weeks by the Rail, Maritime and Transport union in the bitter dispute over the role of conductors.

The latest 48-hour walkout ended on Saturday night, with further stoppages planned later this month, early December, in the run up to Christmas and over new year.

The RMT is also balloting its driver members for strikes.

Southern announced that 215 conductors - 96% of the total - have signed up to the new on-board supervisor role (OBS) from January, which focuses on customer service and moves the operation of closing doors to the driver.

They had until last Friday to respond to Southern's deadline for agreeing to transfer to the new job.

A further 222 people will remain in their existing roles as conductors on certain Southern services.

The train company said it will be recruiting a further 100 OBS roles to work across Southern and Gatwick Express services, with an advertising campaign being launched later this week.

GTR, Southern's parent company, has also confirmed that its formal offer to the RMT to settle the dispute, which has been on the table for three months, has now been formally withdrawn.

GTR had warned the union last week that the offer would be revoked if they went ahead with any further strike action.

Angie Doll, Southern's passenger services director, said: "We're pleased that Aslef has called off this ballot. This welcome development gives us the time and opportunity to sit down with union officials to resolve their dispute.

"We've now got over 200 conductors signed up to the new on-board role and over the last two sets of strikes nearly a third of conductors turned up for work, disproving the union's claims that support is rock solid. Drivers having sole control of the train has been shown over decades of operation to be entirely safe and 15 years of research by independent rail safety experts corroborates this. We'll have a second member of safety-trained staff on more trains than we do today so the RMT's arguments are baseless and vacuous.

"The union leadership has stooped to a new low by calling strike dates over the Christmas period and we know of some conductors who have now resigned their union membership over this selfish, shameful and spiteful act. The union's leadership is maintaining a clear and blatant disregard for workers, families, the elderly and the disabled seeking to be with loved ones over the holiday season. It's a time for Santa and mistletoe, not strikes and misery. The union must think again about their vindictive desire to see Christmas cancelled for the travelling public.

"These past eight months of strikes have had a profound effect on both passengers and our staff. The travelling public is sick and tired of the continuing disruption to their lives and are very angry, and rightly so. But I'd ask them to consider the very difficult position that many employees have been put in during these strikes.

"A large number have defied the picket line to work during the strikes and many others that join the strikes do so under significant peer pressure and with great reluctance."

The RMT says the industrial action continues to be solidly supported.

Mick Cash said: "Nothing has changed in terms of the core issues at the heart of this dispute.

"It's about basic rail safety and access to transport services for all members of our community.

"That ground has not shifted an inch thanks to sheer pig-headed attitude of Southern Rail and their Government pay masters.

"Our members remain rock solid in the fight for safety and access on Southern Rail and will not be bribed, bullied or beaten by this basket case company. That fight goes on."